1. Field of the Invention
This invention relates to a rotary magnetic disc device, and more particularly to a rotary magnetic disc device used in a magnetic recording-reproducing apparatus for an electronic still camera and the like.
2. Description of the Prior Art
Recently, there has been developed an electronic still camera system wherein an image pickup device such as a solid state image sensing device or an image pickup tube is combined with a recording device using an inexpensive magnetic disc as a recording medium and yet having a comparatively high memory capacity, a subject is still-photographed electronically and recorded onto a rotating magnetic disc, and the reproduction of an image is carried out by a television, a printer or the like, which are provided separately. The above-described camera system has become the object of attention.
The magnetic disc used in the above-described camera system is normally used in the form of a magnetic disc pack. The magnetic disc pack is rotatably provided therein with the magnetic disc for magnetically recording still image information and the like, and this magnetic disc pack is used as being mounted to a rotary magnetic disc device assembled in an electronic camera. It is troublesome and inconvenient to directly couple a center hole formed in a center core in the central portion of the magnetic disc of the magnetic disc pack onto a rotary driving shaft on the magnetic recording-reproducing apparatus when the magnetic disc pack is mounted to the magnetic recording-reproducing apparatus in the electronic camera, and there is a possibility of being unable to accurately mount the magnetic disc pack onto the magnetic recording-reproducing apparatus.
To avoid the above-described troublesomeness, there has heretofore been proposed a device for loading or unloading a magnetic disc pack. This device for loading or unloading a magnetic disc pack is of such an arrangement that there is provided a holder openably supported on a main body of the magnetic recording-reproducing apparatus, the magnetic disc pack is inserted into the holder, and thereafter, the holder is closed, so that the magnetic disc of the magnetic disc pack in the holder can be mounted onto the rotary driving shaft of the main body of the apparatus. A center core is formed in the center portion of the magnetic disc and the rotary driving shaft is coupled into this center hole of the center core to thereby rotate the magnetic disc in the magnetic disc pack.
The magnetic disc used in the above-described electronic camera and the like, differing from an ordinary floppy disc, is recorded with high density and rotated at high speed, whereby a head touch differs from the one of an ordinary floppy disc, wherein the disc is urged against the side of a magnetic head through a pad. More specifically, as shown in FIGS. 12 and 13, in the case of the electronic camera and the like, a regulating plate 4 having a recess 2 is opposed to a magnetic head 42, interposing therebetween the magnetic disc 12, and the regulating plate 4 is located at a predetermined position relative to the magnetic head 42, whereby the magnetic disc 12 is lain along the magnetic head 42. Due to this effect of the regulating plate 4, a torque of the magnetic disc 12 can be decreased as compared with the case where urging is performed by the pad of the ordinary floppy disc. However, in the above-described rotary magnetic disc device, the magnetic disc 12 is constantly brought into contact with the outermost peripheral portion 4A of the regulating plate 4, and the magnetic head 42 is positioned in the recess 2 of the regulating plate 4, and moves while being in abutting contact with the magnetic disc 12. At this time, an urging force (the head touch) rendered to the magnetic disc 12 by the magnetic head 42 is varied between the outer periphery and the inner periphery of the magnetic disc 12. This variation in the urging force adversely affects the picture quality during magnetic recording or reproducing. Further-more, in the above-described rotary magnetic recording-reproducing apparatus, it becomes necessary to provide the regulating plate 4 having a length corresponding to the total movement stroke of the magnetic head 42, which, increasing the installation space of the regulating plate 4, presents an obstacle in rendering the electronic camera and the like compact in size.